Small storm, then warm

Small storm, then warm

A combination of storm systems will bring a chance of snow showers to the Institute on Friday, punctuating a streak of milder-than-normal weather.

A deep low pressure system currently over the Great Lakes will merge tomorrow with a coastal storm currently forming off the coast of the Carolinas, spreading the possibility of snow showers across New England in the process. Any accumulation will be small, however — an inch at most — and temperatures climbing to near 40°F (4°C) will likely keep the snow from sticking.

Otherwise, a pattern of relatively warm weather will persist. The temperature at Boston’s Logan Airport broke the 50°F (10°C) mark for the first time in over two weeks on Tuesday, and high temperatures are expected to remain above the climatological normal of 36°F (2°C) for at least the next few days. Medium-range numerical models show an upper-level ridge being positioned over the U.S. East Coast, leading to anomalously warm temperatures, and pushing the tracks of storms further northwest. With storms tracking to the northwest of Boston, the area is more likely to experience warm fronts, and precipitation is more likely to fall as rain rather than snow. While it’s not possible to forecast specifics many days in advance, this general pattern looks to hold at least through next week.

­—Vince Agard

A blizzard in review

As forecasted in the previous issue of The Tech, the Boston area witnessed only a snippet of this weekend’s potent winter storm. The storm dumped over 30 inches of snow at various locations in Mid-Atlantic region, setting numerous records. Early Saturday morning, an unstable atmosphere led to numerous reports of thundersnow, a phenomenon that’s only observed about six times a year in the U.S. Analogous to a summertime thunderstorm, these convective storms are accompanied by lightning, thunder, and sometimes hail stones.

The severity of the blizzard — which caused 48 deaths and roughly a billion dollars in damage — left many asking what contributed to its rapid intensification and maintenance. This weekend’s blizzard drew in warm, energy-rich air modified by what NOAA has noted to be the strongest El Niño on record, which may have contributed its strength. Shortly before the storm intensified, global weather models and satellite data revealed an influx of warm, moist air originating above Pacific ocean waters about 2 °C above average. East Coast winter weather systems are typically driven by temperature and moisture gradients between relatively warm oceanic air over the Atlantic and cool continental air near the coast. With a powerful high pressure system over the northeastern U.S. plunging cold air southward and warm oceanic air being drawn inland, the winter storm quickly intensified and broke numerous snowfall records.

—Costa Christopoulos